JP5241172B2 - Developer, developer cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to a developer used in an image forming apparatus such as an electrophotographic printer.

An electrophotographic printer is used as a kind of image forming apparatus. In the printer, toner for forming an image is used as a developer. This toner is generally formed by adding a charge control agent and a release agent to a mixture of a binder resin and a colorant.
Wax is used as a release agent, and has a function of ensuring separation from the heating member used during image fixing. Further, the charge control agent has a function of controlling the chargeability of the toner in order to give the toner a desired charge amount.

As this charge control agent, conventionally, a metal complex of a negatively chargeable salicylic acid derivative has been used.
By the way, when only such a negatively chargeable charge control agent is used, the saturated charge amount of the toner becomes excessively high, and when the image printing operation is continued, the increase in the charge amount of the toner causes a so-called background stain. That is, a phenomenon called smear occurs.

In order to eliminate such a phenomenon, Patent Document 1 listed below discloses a charge control agent having a reverse chargeability (that is, positive chargeability), for example, a quaternary ammonium salt (hereinafter referred to as CCA8), and a charge control agent having a negative chargeability. A technique for forming a toner by mixing with a toner is disclosed. Thereby, the saturation charge amount of the toner can be suppressed.
JP 11-242358 A

However, when both charge control agents having opposite polarities as described above are used together, the negative charge performance of the negative charge control agent is relatively lowered due to the actual temperature and humidity, and the development roller Inadequate toner layer formation may occur. Therefore, problems such as covering, density reduction, color spots, and print rubbing occur in the printed image.
Therefore, in order to obtain good printing, a toner capable of having an appropriate charge amount at the time of image formation is desired.

The present invention adopts the following configuration in order to solve the above points.
<Configuration 1>
A developer according to the present invention is a developer used in an image forming apparatus, and has a first charge control agent having a property indicating a predetermined polarity and a first charge amount, a predetermined polarity, and A second charge control agent having a property of exhibiting a second charge amount lower than the first charge amount, wherein the first charge control agent is a salicylic acid derivative Zn compound, a salicylic acid derivative Al compound, and a salicylic acid derivative. Wherein the second charge control agent comprises at least one of a calex arene compound, a K salt of a benzylic acid derivative, an organic polymer, and a basic dye, The control agent and the second charge control agent are mixed in a ratio of X: Y and 0 <X < 1 , 3 ≧ Y ≧ 1 . 5, wherein the Der Turkey.

<Configuration 2>
In addition, a developer cartridge according to the present invention is characterized by containing the developer described in the first configuration .

<Configuration 3>
Furthermore, an image forming apparatus according to the present invention includes the developer cartridge described in the above configuration 2 .

  According to the developer of the present invention, at least two kinds of charge control agents are mixed, and the two kinds of charge control agents have the same polarity, so that an appropriate charge amount can be obtained at the time of image formation. As a result, good printing can be obtained.

  Hereinafter, the developer according to the present invention will be described in detail with reference to embodiments using the drawings.

FIG. 1 is an explanatory diagram showing a configuration of a developer according to the present invention.
The developer 10 according to the present invention is applied to, for example, an electrophotographic printer, and as shown in FIG. 1, a binder resin 11, a colorant 12, a release agent 13, and a first type charge control. An agent 14, a second type charge control agent 15, and an external additive 16 are contained.

  The binder resin 11 is made of any of amorphous polyester, amorphous polyester polyamide, and amorphous styrene acrylic resin. In the present invention, an amorphous polyester is preferable from the viewpoints of fixability and durability. The softening point of the amorphous resin is preferably 80 to 170 ° C, the maximum peak temperature of the heat of fusion is preferably 55 to 80 ° C, the glass transition point is preferably 55 to 75 ° C, and the chloroform insoluble fraction is preferably Is 0 to 50% by weight, and the oxidation value is preferably 5 to 30 mgKOH / g. The glass transition point is a physical property unique to an amorphous resin and is different from the maximum peak temperature of heat of fusion.

The binder resin 11 is formed by the procedure described below.
That is, propylene oxide adduct of bisphenol A as raw material monomer (average addition 2.2 mol): 1.4 kg, ethylene oxide adduct of bisphenol A (average addition 2.2 mol): 1.3 kg, 700 g of fumaric acid, trimellitic anhydride 400 g of acid and 4 g of dibutyltin oxide were placed in a 5-liter four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple, reacted at 220 ° C. for 8 hours, The reaction was continued at 3 kPa until the softening point reached 145 ° C. The obtained resin has a glass transition point of 61 ° C. and a maximum peak temperature of heat of fusion of 65 ° C. In addition, if a polyester resin having the same thermal characteristics is used, a substantially equivalent result can be obtained even if a commercially available product is used.

Next, an example of a method for measuring the softening point will be described below.
Using a Koka type flow tester (manufactured by Shimadzu Corporation, CFT-500D), a 1 g sample was heated at a heating rate of 6 ° C./min. A nozzle with a length of 1 mm is pushed out, thereby drawing a plunger tester drop amount (flow value) -temperature curve of the flow tester. When the height of the S-curve is h, the temperature corresponding to h / 2 (resin The temperature at which half of the effluent flowed out) is taken as the softening point.

Examples of methods for measuring the maximum peak temperature of the heat of fusion and the glass transition point are described below.
Using a differential scanning calorimeter (DSC210, manufactured by Seiko Denshi Kogyo Co., Ltd.), a sample heated to 200 ° C. and cooled to 0 ° C. at a cooling rate of 10 ° C./min was measured at a heating rate of 10 ° C./min. And determine the maximum peak temperature of the heat of fusion. The glass transition point is defined as the temperature at the intersection of the base line extension below the maximum peak temperature in the measurement and the tangent line indicating the maximum slope from the peak rising portion to the peak apex.

In the developer 10, the colorant 12 is made of, for example, a pigment such as a blue pigment ECB-301 (manufactured by Dainichi Seika Co., Ltd.) or a dye. That is, the colorant 12 is carbon black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B base, solvent red 49, solvent red 146, solvent blue 35, quinacridone, carmine 6B, disazo yellow. Among them, it is formed of one kind or a mixture of two or more kinds.
The developer 10 according to the present invention is used as a black toner, a color toner, or a full-color toner. In this embodiment, the developer 10 is a full-color toner containing an organic pigment. In this case, the content of the organic pigment is set to 3 to 10 parts by weight.

  The release agent 13 is made of wax, and it is desirable to use a wax having a desired melting point of 50 to 120 ° C. as the wax. The wax has good compatibility with the polyester resin, and in this embodiment, carnauba wax C1 (manufactured by Kato Yoko Co., Ltd.) having a melting point of 83 ° C. is used. Wax is used as a release agent, and has a function of ensuring separation from a heating member used at the time of image fixing, and the content thereof is 2 to 10 weights with respect to 100 parts by weight of the binder resin. Part is preferred.

  In addition, the electrophotographic toner of this embodiment includes a conductive filler, extender pigments, reinforcing fillers such as fibrous substances, antioxidants, anti-aging agents, fluidity improvers, and cleaning property improvers. An agent may be appropriately contained.

In the developer 10, the first type charge control agent 14 and the second type charge control agent 15 have the same polarity. As a charge control agent, these have a function of controlling the chargeability of the toner so that the toner has a desired charge amount.
In this embodiment, this same polarity is negative. That is, these charge control agents have the property of exhibiting a negative charge amount.
FIG. 2 is an explanatory diagram of the first and second type charge control agents.
The first type of charge control agent 14 can be formed of a metal complex of at least one salicylic acid derivative. That is, as shown in FIG. 2, the first type of charge control agent 14 is composed of a salicylic acid derivative Zn compound (CCA1), a salicylic acid derivative Al compound (CCA2), and a salicylic acid derivative as shown in FIG. Among Zr compounds (CCA3), it is formed of one compound or two or more compounds.

  As the second type charge control agent 15, it is formed of at least one material among a calexarene compound (CCA4), a K salt of a benzylic acid derivative (CCA5), an organic polymer (CCA6) and a basic dye (CCA7). be able to.

FIG. 3 is a charge amount comparison graph of each charge control agent.
As shown in FIG. 3, a salicylic acid derivative Zn compound (CCA1), a salicylic acid derivative Al compound (CCA2), and a salicylic acid derivative Zr compound (CCA3) have a relatively high charge amount as each charge control agent. Calexarene compound (CCA4), K salt of benzylic acid derivative (CCA5), organic polymer (CCA6) and basic dye (CCA7) exhibit a relatively low charge amount as each charge control agent. .
That is, the salicylic acid derivative Zn compound (CCA1), the salicylic acid derivative Al compound (CCA2), and the salicylic acid derivative Zr compound (CCA3) constitute a group with a high charge amount. The calexarene compound (CCA4) and the benzylic acid derivative The K salt (CCA5), the organic polymer (CCA6) and the basic dye (CCA7) constitute a low charge amount group.
The content of each charge control agent in the developer 10 (FIG. 3) is set, for example, with respect to 100 parts by weight of the binder resin 11.

  In the present invention, the first type charge control agent 14 is formed of one or more materials among the CCA1 to CCA3 in the high charge amount group, and thus has a property of exhibiting a high charge amount. Further, since the second type charge control agent 15 is formed of one or two or more materials among CCA4 to CCA7 in the low charge amount group, it has a property of exhibiting a low charge amount.

FIG. 4 is a charge amount comparison graph of each charge control agent in a group having a high charge amount when CCA 4 is mixed.
As shown in FIG. 4, when 1 part by weight of CCA4 is mixed with each of CCA1 to CCA3 in the high charge amount group, if the parts by weight of CCA1 to CCA3 are set to 1.0 or less, Each charge amount is −30 μC / g or less. In this case, it has been found that there is an effect of suppressing the saturation charge amount to −30 μC / g or less.
In addition, each content (FIG. 4) of CCA4 and CCA1-CCA3 in the developer 10 is set with respect to 100 parts by weight of the binder resin 11, for example.

FIG. 5 is a charge amount comparison graph of each charge control agent in the low charge amount group when CCA1 is mixed.
As shown in FIG. 5, when 0.5 parts by weight of CCA1 is mixed with each of CCA4 to CCA7 in the low charge amount group, when the parts by weight of CCA4 to CCA7 are set to 1.0 or more, Each of the corresponding charge amounts is −20 μC / g to −30 μC / g. In this case, it has been found that the saturation charge amount can be suppressed to -30 μC / g or less, and good printing with a stable charge amount can be obtained.
In addition, each content (FIG. 5) of CCA1 and CCA4-CCA7 in the developer 10 is set with respect to 100 parts by weight of the binder resin 11, for example.

In this embodiment, the first type charge control agent 14 uses only a Zn compound (CCA1) of a salicylic acid derivative, and the second type charge control agent 15 uses only a calexarene compound (CCA4).
Hereinafter, the quality of an image formed by applying the developer 10 formed by mixing the CCA1 and CCA4 to an electrophotographic printer will be described.
The following contents (FIG. 6) of CCA1 and CCA4 in the developer 10 are set with respect to 100 parts by weight of the binder resin 11, for example.

FIG. 6 is an explanatory diagram for evaluating the image quality when CCA1 and CCA4 are mixed.
As shown in FIG. 6, the content of CCA1 exceeds 0 part by weight, but is set to be less than 2 parts by weight and the content of CCA4 is set to exceed 0.5 parts by weight. , Problems such as the occurrence of dirt on the image are eliminated.
In particular, when the content of CCA1 is set to 0.5 to 1 part by weight and the content of CCA4 is set to 1 to 3 parts by weight, the image quality can be further improved.
Further, when the content of CCA4 is set to 1.5 parts by weight or more and the ratio of CCA4 to CCA1 is set to 2: 1, even better printing can be obtained.

In this embodiment, the first type charge control agent 14 uses only a salicylic acid derivative Zn compound (CCA1). Instead, the salicylic acid derivative Al compound (CCA2) or the salicylic acid derivative Zr compound (CCA3) can be employed as the first type of charge control agent 14.
Further, as the first type charge control agent 14, two or more compounds, for example, a mixture of a salicylic acid derivative Zn compound (CCA1) and a salicylic acid derivative Al compound (CCA2), a salicylic acid derivative Al compound (CCA2) and Mixture of salicylic acid derivative Zr compound (CCA3), salicylic acid derivative Zn compound (CCA1) and salicylic acid derivative Zr compound (CCA3), or salicylic acid derivative Zn compound (CCA1) and salicylic acid derivative Al compound ( A mixture of CCA2) and a Zr compound (CCA3) of a salicylic acid derivative can be employed. In this case, the content of the mixture is set similarly to the case of the salicylic acid derivative Zn compound (CCA1) alone.

  In the present embodiment, the second type charge control agent 15 uses only a calexarene compound (CCA4). Alternatively, the benzylic acid derivative K salt (CCA5), organic polymer (CCA6), or basic dye (CCA7) may be employed as the second type charge control agent 15, and the calexarene compound (CCA4). Alternatively, a mixture of two or more materials among the K salt of benzylic acid derivative (CCA5), the organic polymer (CCA6) and the basic dye (CCA7) may be employed. When the mixture is employed, the content is set in the same manner as in the case of the calex arene compound (CCA4) alone.

  The external additive 16 (FIG. 1) contained in the developer 10 has functions such as charging assistance, charge retention, and ensuring the fluidity of the developer 10, such as hydrophobic silica TS. -530 (average particle size 8 nm, manufactured by Cabot) and hydrophobic silica NAX-50 (average particle size 30 nm, manufactured by Nippon Aerosil Co., Ltd.).

Hereinafter, the formation of the developer 10 will be described.
In this embodiment, in the developer 10, the binder resin 11 is 100 parts by weight, the colorant 12 is 5 parts by weight, the mold release agent 13 is 4 parts by weight, and the first type charge control agent 14 is 0.2 parts by weight. The second type charge control agent 15 is set to 1.5 parts by weight at 75 parts by weight.

  First, the binder resin 11, the colorant 12, the release agent 13, the first type charge control agent 14, and the second type charge control agent 15 are mixed by a Henschel mixer, and then, by a co-rotating twin screw extruder. Melted and kneaded. At this time, the total length of the kneading part is 1560 mm, the screw diameter is 42 mm, the barrel inner diameter is 43 mm, the roll rotation speed is 200 revolutions / minute, the heating temperature in the roll is 100 ° C., The feed rate is 10 kg / hour and the average residence time is about 20 seconds.

  Thereafter, cooling and coarse pulverization are sequentially performed. Subsequently, a pulverization process is performed so that the volume average particle size becomes 7.5 μm by a jet type pulverizer IDS-2 (manufactured by Nippon Pneumatic Industry), and further fine powder classification is performed by an airflow classifier. . Thereby, a powder having a volume average particle diameter of 8.2 μm was obtained.

Then, to 100 parts by weight of the obtained powder, 0.8 part by weight of hydrophobic silica TS-530 (average particle size 8 nm, manufactured by Cabot) as an external additive 16, and hydrophobic silica NAX-50 (average) Developer 10 as a toner was obtained by adding 1.2 parts by weight of a particle size of 30 nm, manufactured by Nippon Aerosil Co., Ltd., and mixing with a Henschel mixer. When the obtained developer 10 was observed with a particle image analyzer FPIA-2000 (manufactured by Sysmex Corporation), the average sphericity was 0.945.
The configuration of the developer 10 is shown in FIG.

When the developer 10 having such a configuration is applied to an image forming apparatus such as an electrophotographic printer, good printing can be obtained.
FIG. 7 is a configuration diagram of a printer to which the developer according to the present invention is applied.
As shown in FIG. 7, in the printer 20, a developing unit 22 in which a toner tank 21 is mounted is detachably incorporated in a central portion in the printer main body 23. The uppermost part of the printer main body 23 is covered with a cover 24, and the cover 24 is mounted so as to be openable and closable upward. When the cover 24 is opened upward, the developing unit 22 is exposed, and the developing unit 22 can be taken out together with the toner tank 21 upward in the figure.

A paper cassette 26 in which the print medium 25 can be incorporated is disposed at the lower part of the printer main body 23, and the print medium 25 is fed to the entry side with respect to the medium print direction (from right to left in the drawing) of the developing unit 22. A sheet feeding roller group 27 is arranged.
A fixing unit 28 composed of a heating element and a heat-resistant rubber roller is disposed on the discharge side of the developing unit 22 with respect to the medium printing direction (from right to left in the figure). A paper discharge roller group 29 for discharging is disposed on the upper portion of the main body 23.

  An LED exposure head 30 that exposes a photosensitive drum built in the developing unit 22 is disposed above the developing unit 22, and below the developing unit 22, in order to transfer the toner image on the photosensitive drum to a print medium, A transfer roller 31 composed of a conductive sponge and a metal shaft is disposed.

FIG. 8 is a configuration diagram of a developing unit in a printer to which the developer according to the present invention is applied.
As shown in FIG. 8, in the developing unit 22, a charging roller 33 made of conductive rubber and a metal shaft, a developing roller 34, and a cleaner 38 made of a urethane rubber blade are in contact with the outer periphery of the photosensitive drum 32. Has been placed. Further, the LED exposure head 30 is disposed above the photosensitive drum 32 so as to face the photosensitive drum 32.

Further, a supply roller 35 and a developing blade 36 for supplying the developer 10 as toner are arranged on the developing roller 34 so as to contact the developing roller 34.
The toner tank 21 contains the developer 10 that is toner. A stirring blade 37 for stirring the toner is disposed below the toner tank 21.
The toner tank 21 contains a developer according to the present invention as a developer cartridge.

The developer 10 that is toner is conveyed from the toner tank 21 to the supply roller 35 via the stirring blade 37 and is supplied to the development roller 34 by the supply roller 35. The supplied toner is selectively moved to the photosensitive drum 32 while adhering to the developing roller 34. That is, based on the electrostatic latent image formed on the photosensitive drum 32, the toner moves from the developing roller 34 to the photosensitive drum 32, and a toner image is formed.
This toner image is transferred to the print medium 25 by the transfer roller 31 and fixed by the fixing unit 28. This completes image formation, that is, printing.

  In such image formation, the developer according to the present invention is used as the toner, and two kinds of charge control agents are mixed in the developer, and the two kinds of charge control agents have the same polarity. Therefore, an appropriate charge amount can be obtained at the time of image formation, and as a result, good printing can be obtained.

Next, the effects of the developer according to the present invention will be compared and explained using comparative experiments.
First, as a result of a printing test using a toner sample that contains only CCA1 and has been changed in its content, the toner charge amount (charge amount per unit volume) increases to an absolute value greater than -30 μC / g. It was found that the toner was developed on the non-image area by the potential of the toner itself, resulting in a background stain.

  Moreover, CCA1 containing 1 part by weight of CCA1 and showing positive (reverse) charging together (refer to the background art described above), that is, containing quaternary ammonium salt (BONTRON P51, manufactured by Orient Chemical Co., Ltd.) As a result of a printing test using a toner sample manufactured by changing the amount of toner, when the toner charge amount (charge amount per unit mass) decreases to an absolute value lower than −20 μC / g, the charge amount becomes insufficient, and the developing roller It was found that the electrostatic adhesion force to the surface was reduced, rubbing, and density reduction occurred. Furthermore, when the toner charge amount (charge amount per unit volume) is lower than −15 μC / g, the total toner charge amount becomes insufficient, and electrostatic repulsion between negative potentials on the non-image area. It has also been found that so-called covering occurs.

FIG. 16 is an explanatory diagram for evaluating the image quality when CCA1 and CCA8 are mixed in a comparative experiment.
As shown in FIG. 16, when the toner formed by mixing CCA1 and CCA8 having different polarities is applied to an image forming apparatus, there are many phenomena such as the occurrence of rubbing, the occurrence of dirt, and the occurrence of covering as described above. I found out.

In contrast, when the toner formed by mixing CCA1 and CCA4 having the same polarity is applied to the image forming apparatus as shown in FIG. 6, the CCA1 and CCA4 are shown in FIGS. 5 has the characteristics as shown in FIG. 5, it was found that phenomena such as rubbing, dirt, and covering were suppressed.
In particular, as described above, when the content of CCA1 is set to less than 2 parts by weight and the content of CCA4 is set to 0.5 parts by weight or more, problems such as the occurrence of stains do not exist on the image. Further, when the content of CCA1 is set to 0.5 to 1 part by weight and the content of CCA4 is set to 1 to 3 parts by weight, the image quality can be further improved, and the content of CCA4 is further set to 1 If the ratio is set to 5 parts by weight or more and the ratio of CCA4 to CCA1 is set to 2: 1, even better printing can be obtained.

  As a supplement, it goes without saying that the upper limit of the amount of CCA added is in the practical range of so-called general common sense. That is, for example, when the amount of CCA added exceeds 10 parts by weight, not only is it not uniformly dispersed in the toner, but also the polyester resin is crosslinked to change the properties of the resin itself (for example, the heat of fusion properties).

  The toner charge amount was measured in the image forming apparatus of this example by setting the printing speed of the medium to 200 mm / s as the linear speed and printing 1000 blank paper prints so as not to consume the toner. Thereafter, the toner on the developing roller was sampled by a suction type Faraday cage 210HS (manufactured by Trek), and the charge amount per unit mass was obtained by dividing the observed charge amount by the sucked toner mass.

  In addition, the printing evaluation performed here was performed with the above printing speed, with the upper half of the A4 paper being blank and the rear half being solid (maximum density on the entire surface). Judgment of color spots, rubbing, etc.

  As described above, when CCA4 having low charge characteristics is mixed with CCA1 having high charge characteristics at the above-described mixing ratio, the charge amount of the entire toner can be easily set to -30 μC / g or less. In addition, the toner particles can be prevented from changing to positive polarity even under the influence of temperature and humidity, and the charge amount of the whole toner can be prevented from being reduced to -20 μC / g or less, and therefore the quality is excellent. Printing can be performed.

In Example 1 described above, carnauba wax C1 (manufactured by Kato Yoko Co., Ltd.) having a melting point of 83 ° C. was employed as the release agent 13. In this embodiment, paraffin wax FT100 (manufactured by Nippon Seiwa Co., Ltd.) having a melting point of 98 ° C. is employed as the release agent 13.
Further, the content of the paraffin wax FT100 is set to 4 parts by weight with respect to 100 parts by weight of the binder resin 11 as in Example 1.
In this embodiment, the toner, that is, the method for producing the developer 10, the operation of the image forming apparatus, and the like are the same as those in the first embodiment, and thus description thereof is omitted.

FIG. 9 is a comparative graph of fixing separability of each release agent in Example 2.
As shown in FIG. 9, when the carnauba wax C1 is used, the good fixing range is narrow. Therefore, if the toner adhesion amount on the paper surface is large, the molten toner adheres to the heat of the fixing device on the high temperature side. As a result, a phenomenon of redeposition on the paper surface, that is, a so-called offset occurs, which may cause a separation failure between the fixing device and the medium.

  On the other hand, when paraffin wax FT100 is employed, the good fixing range is greatly expanded. Thereby, the fixing separation property on the high temperature side is improved.

  That is, when the wax is C1, a so-called offset occurs in which the melted toner adheres to the heat of the fixing device and reattaches to the paper surface, particularly on the high temperature side when the toner adhesion amount on the paper surface is large. In severe cases, separation failure between the fixing device and the medium occurs. On the other hand, when the wax is FT100, it can be seen that this fixable region is greatly enlarged on the high temperature side.

A method for evaluating the fixing performance is described below.
At the above printing speed, the developing bias applied to the developing roller was adjusted, and the toner adhesion amount on the paper surface on the solid printing was set to 0.5 mg / cm ² . At this time, the developing bias was about 210V. Then, the set temperature of the heat roller was adjusted in the fixing device, and the fixing performance at each temperature was measured. The print pattern used for this measurement is a solid 4 cm print on the top of A4 paper. On the low temperature side, the toner is melted and fixed on the paper surface. On the high temperature side, offset toner is not confirmed on the blank paper at the trailing edge of the paper. Also, it was confirmed whether the separation was insufficient and the medium was likely to be caught.
The toner adhesion amount of 1.5 mg / cm ² on the paper surface was not formed at a time, so the fixing device was removed and printing was repeated three times on the same medium.

Hereinafter, when the paraffin wax FT100 is employed, the charge amount of each charge control agent formed by mixing the first type charge control agent 14 and the second type charge control agent 15 will be described.
FIG. 10 is a charge amount comparison graph of each charge control agent in Example 2.
FIG. 10 shows the chargeability in each case where 1 part by weight of the calexarene compound (CCA4) was mixed and in each case where 0.5 part by weight of the Zn compound (CCA1) of the salicylic acid derivative was mixed. ing.
FIG. 10 also shows the chargeability when only CCA1 (CCA4: 0 parts by weight) is contained.

  From FIG. 10, as in Example 1, the content of the first type charge control agent 14 is set to 1.0 part by weight or less with respect to 100 parts by weight of the binder resin 11, and the second type It can be found that it is optimal to set the charge control agent 15 to 1.5 parts by weight. Thereby, the saturation charge amount can be suppressed to −30 μC / g or less.

  Further, when comparing FIG. 10 with the above-described FIG. 3 (comparison between the charging characteristics of CCA1 when the content of CCA4 in FIG. 10 is 0 part by weight and the charging characteristics of CCA1 in FIG. 3), only CCA1 is compared. When (CCA4: 0 part by weight) is contained, the charge amount increases, which is presumed to be the influence of the wax, which is the change point here, and in any sample, the charge amount increases. I can see the tendency.

FIG. 11 is an explanatory diagram for evaluating the image quality when CCA1 and CCA4 are mixed in the second embodiment.
As shown in FIG. 11, the content of CCA1 is set to 1.0 or less, the content of CCA4 is set to 1.5 parts by weight or more, and the ratio between CCA4 and CCA1 is 2 When set to 1, excellent printing can be obtained.

  In this embodiment, the developer according to the present invention is formed by containing two types of charge control agents having the same polarity and a release agent made of paraffin wax FT100. As a result, it is possible to obtain a good charge amount and obtain a good print, and to improve the fixing separation property on the high temperature side.

  In the present embodiment, the toner charge amount measuring method and the print evaluation method are the same as those in the first embodiment, and thus description thereof is omitted.

In Example 2 described above, only the paraffin wax FT100 having a melting point of 98 ° C. is employed as the release agent 13. In this embodiment, as the release agent 13, paraffin wax FT100 having a melting point of 98 ° C. and polyethylene wax are used in combination.
Further, the content of the paraffin wax FT100 is set to 4 parts by weight with respect to 100 parts by weight of the binder resin 11, and 2 parts of high wax 100P (manufactured by Mitsui Chemicals) having a melting point of 110 ° C. as polyethylene wax is used. Use parts.

As described above, when the wax is further used in combination with the paraffin wax and the polyethylene wax, further improvement in the durability (printing durability) of the toner is expected while improving the fixing separation property on the high temperature side as it is. This is presumably because the polyester wax has an effect of assisting the dispersion of the paraffin wax in the binder resin, the particle diameter of the dispersed wax is 1 μm or less, and the mechanical strength of the toner is increased.
In this embodiment, the toner, that is, the method for producing the developer 10, the operation of the image forming apparatus, and the like are the same as those in the first embodiment, and thus description thereof is omitted.

FIG. 12 is a comparison graph of fixing separability of release agents in Example 3.
As shown in FIG. 12, the good fixing range when the paraffin wax FT100 and the high wax 100P are used together is substantially the same as the good fixing range when only the paraffin wax FT100 is used. That is, even when the paraffin wax FT100 and the high wax 100P are used in combination, a good fixing separation property can be obtained.
In the present embodiment, the fixing performance evaluation method is the same as that in the second embodiment, and a description thereof will be omitted.

FIG. 13 is a comparison graph of the printing durability of the developer corresponding to each release agent in Example 3.
As shown in FIG. 13, when the paraffin wax FT100 and the high wax 100P are mixed and used together, the developer 10 as a toner can print up to 5000 print media with a cartridge life without any problem, and the paraffin wax Compared to the case where only the wax FT100 is used, the printing durability, that is, the durability is greatly increased.

  In this durability evaluation method, a printing pattern composed of only alphabets and having a coverage of 5% is continuously printed at the above-mentioned printing speed, and the entire surface is printed on A4 paper every 500 sheets. Judgment was made by presence or absence.

Hereinafter, when the paraffin wax FT100 and the high wax 100P are mixed and used together, the charge amount of each charge control agent formed by mixing the first type charge control agent 14 and the second type charge control agent 15 is described below. explain.
FIG. 14 is a charge amount comparison graph of each charge control agent in Example 3.
FIG. 14 shows the chargeability in each case where 1 part by weight of the calex arene compound (CCA4) was mixed and in each case where 0.5 part by weight of the Zn compound (CCA1) of the salicylic acid derivative was mixed. Yes.
FIG. 14 also shows the chargeability when only CCA1 (CCA4: 0 parts by weight) is contained.

  From FIG. 14, as in Examples 1 and 2, the content of the first type charge control agent 14 is set to 1.0 part by weight or less with respect to 100 parts by weight of the binder resin 11, and the second It can be seen that it is optimal to set the seed charge control agent 15 to 1.5 parts by weight. Thereby, the saturation charge amount can be suppressed to −30 μC / g or less.

  14 is compared with the above-described FIG. 3 (comparison between the charging characteristics of CCA1 when the content of CCA4 in FIG. 14 is 0 part by weight and the charging characteristics of CCA1 in FIG. 3), only CCA1 ( CCA4: 0 parts by weight) increases the charge amount, which is presumed to be the effect of wax, which is the change point here, and in any sample, the charge amount increases. I can see a tendency to

FIG. 15 is an explanatory diagram for evaluating the image quality when CCA1 and CCA4 are mixed in the third embodiment.
As shown in FIG. 15, the content of CCA1 is set to 1.0 or less, the content of CCA4 is set to 1.5 parts by weight or more, and the ratio between CCA4 and CCA1 is 2 When set to 1, excellent printing can be obtained.

  In this embodiment, the developer according to the present invention is formed by including two types of charge control agents having the same polarity and a release agent formed by mixing paraffin wax FT100 and high wax 100P. Therefore, an appropriate charge amount can be obtained at the time of image formation to obtain a good print, the fixing separation property on the high temperature side can be improved, and the printing durability of the developer 10 as a toner can be improved. .

  The developer according to the present invention is applied to a contact development type printer in which a photosensitive drum and a development roller are in contact with each other. However, a partial contact development type or a non-contact development type (a so-called jumping development type) is used. It can also be applied to a printer (image forming apparatus).

  Further, the developer according to the present invention is applied to a printer in which a photosensitive drum and a developing roller are housed and arranged together in a developing unit. However, a printer in which the photosensitive drum and the developing roller are independently arranged ( It can also be applied to an image forming apparatus.

  Further, the developer according to the present invention can be applied to an image forming apparatus for single color printing and an image forming apparatus for color printing. Become.

It is explanatory drawing which shows the structure of the developing agent which concerns on this invention. It is explanatory drawing of a 1st type and a 2nd type charge control agent. It is a charge amount comparison graph of each charge control agent. When CCA4 is mixed, it is a charge amount comparison graph of each charge control agent in a high charge amount group. It is a charge amount comparison graph of each charge control agent in the group of a low charge amount when CCA1 is mixed. It is explanatory drawing for evaluating the image quality at the time of mixing CCA1 and CCA4. 1 is a configuration diagram of a printer to which a developer according to the present invention is applied. FIG. It is a block diagram of the developing unit in the printer to which the developer according to the present invention is applied. 6 is a graph for comparison of fixing and separating properties of release agents in Example 2. 6 is a charge amount comparison graph of each charge control agent in Example 2. FIG. It is explanatory drawing for evaluating the image quality at the time of mixing CCA1 and CCA4 in Example 2. FIG. 7 is a graph showing comparison of fixing and separating properties of release agents in Example 3. 6 is a comparative graph of printing durability of a developer corresponding to each release agent in Example 3. 6 is a charge amount comparison graph of each charge control agent in Example 3. It is explanatory drawing for evaluating the image quality at the time of mixing CCA1 and CCA4 in Example 3. FIG. It is explanatory drawing for evaluating the image quality at the time of mixing CCA1 and CCA8 in a comparative experiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Developer 11 Binder resin 12 Colorant 13 Release agent 14 1st type charge control agent 15 2nd type charge control agent 16 External additive

Claims (9)

A developer used in an image forming apparatus,
A first charge control agent having a property of exhibiting a predetermined polarity and a first charge amount;
A second charge control agent having the predetermined polarity and having a property of exhibiting a second charge amount lower than the first charge amount;
The first charge control agent includes at least one of a salicylic acid derivative Zn compound, a salicylic acid derivative Al compound and a salicylic acid derivative Zr compound,
The second charge control agent includes at least one of a calex arene compound, a K salt of a benzylic acid derivative, an organic polymer, and a basic dye,
The first charge control agent and the second charge control agent are mixed in a ratio of X: Y, and 0 <X < 1 , 3 ≧ Y ≧ 1 . Ru 5 Der
Developing agent characterized a call.   The developer according to claim 1, wherein X: Y is set to 1: 2.   The developer according to any one of claims 1 to 2, further comprising a binder resin, a colorant, and a release agent.   4. The developer according to claim 3, wherein the release agent is formed by mixing paraffin wax and polyethylene wax.   The developer according to claim 3, wherein the release agent is made of carnauba wax.   The developer according to claim 3, wherein the release agent is made of paraffin wax.   The developer according to claim 1, wherein the predetermined polarity is negative.   A developer cartridge containing the developer according to any one of claims 1 to 7.   An image forming apparatus comprising the developer cartridge according to claim 8.

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